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4 posts from August 2012


HTTP Monitors Behave Differently in BigIP LTM v10/v11

I needed to create a custom http monitor for an Adobe CQ implementation. Having upgraded our environment from v9 to v10 (and then v11) only fairly recently, this was my first time having to set up a custom http monitor on our BigIPs because none of my existing monitors was suitable.

The first thing I noticed post v10 upgrade was that the Send String in the default monitors had changed to include a carriage return/line feed (CRLF) after the resource, (i.e. from GET / to GET /\r\n). A typical CQ implementation may include Apache web servers as your customer- or internet-facing systems while your internal publishing servers may continue running the java container identified as Day-Servlet-Engine/4.1.24.

If everything is working as expected, a request to resource /sample/resource/page.html against your customer-facing web servers should also work against your publishing servers. So, I set up a monitor that performed periodic GET requests for /sample/resource/page.html. The send string in the http monitor looked similar to this: GET /sample/resource/page.html\r\n

When applied to the apache pool, the monitor worked as expected but the same monitor applied to the publishing tier resulted in disabled servers. cURL requests for the exact same resource worked as expected against servers in both pools. The only thing that wouldn't work was the http monitor against the publishing servers.

As it turned out, two CRLF's needed to be sent to the cq publishing server http listener, but, luckily, changing the send string in the http monitor from GET /sample/resource/page.html\r\n to GET /sample/resource/page.html\r\n\r\n worked fine against both Apache and the Day servlet engine.

Note to Self: Some app servers need two CRLFs in the http monitor.


Apache HTTP Server 2.4.3 Released

The Apache HTTP Server project announced the availability of version 2.4.3 today. This release contains fixes for two security vulnerabilities, one involving mod_proxy_ajp/mod_proxy_http and the other involving mod_negotiation. In addition to the security vulnerabilities fixed in this release, this new version fixes quite a few bugs. Refer to the Apache 2.4.3 ChangeLog for more details.

You can download copies from a mirror near you via the Apache HTTP Server Downloads page.


8 Ways to Improve Your Java EE Support Skills

Great post from Pierre-Hugues Charbonneau: 8 Ways to Improve Your Java EE Support Skills

My favorite (funny) quote from the article:

One of the great things about Java EE production support is the multiple learning opportunities you are exposed to.

One of the many important tips and points made in the article includes this one in regards to administrators general reluctance when making production changes:

Finally, if you feel that you are lacking technical knowledge to implement the changes, simply say it and ask for another more experienced team member to shadow your work.